Machine Type Communication (MTC), also referred to as Machine to Machine (M2M) communications, refers to wireless and wired communications between devices. MTC has a wide range of applications, including industrial automation, logistics, monitoring but also for control purposes.
MTC is widely used for industrial instrumentation applications in which a device, such as a sensor or meter, captures real-time data, such as temperature, inventory level, error reports, surveillance images, etc., and transmits the captured data to a data collection node. In addition to instrumentation, MTC is also being widely adopted for other applications, such as telemetry and automation.
MTC may incorporate the transmission of many types of information, including user data, signaling information, measurement data, configuration information, etc. The device size may vary from that of a wallet to that of a base station. M2M devices are quite often used for applications, such as sensing environmental conditions (e.g. temperature reading), metering or measurement (e.g. electricity usage etc.), fault finding or error detection, etc. In these applications the MTC devices are active very seldom but over a consecutive duration depending upon the type of service e.g. about 200 ms once every 2 seconds, about 500 ms every 60 minutes etc. The MTC device may also do measurement on other frequencies or other Radio Access Technologies (RATs).
One category of MTC devices is referred to as “low cost devices.” For example, a cost reduction can be realized by relaxing the requirements on peak rate and receiver performance. LTE Release 12 introduces a low cost user equipment (UE) category called UE category 0 with a relatively low peak rate of 1 Mbps and relaxed performance requirements that can be fulfilled having just a single antenna receiver in the UE. The cost can be further reduced by supporting only half duplex frequency division duplexing (FDD) capability instead of full duplex FDD capability. The latter feature prevents the need for having duplex filter since UE does not transmit and receive at the same time.
The RF bandwidth (BW) of the legacy LTE UE is 20 MHz. In legacy LTE systems, the UE reception BW and cell transmission BW have the same center frequencies. Similarly, in legacy LTE system, the UE transmission BW and cell reception BW have the same center frequencies. However, cost reduction may be achieved by having a reduced UE RF bandwidth. For example, for LTE Release 13, cost reduction may be realized by having a reduced UE RF bandwidth of 1.4 MHz comprising six (6) resource blocks (RBs).
For MTC UEs with reduced RF bandwidth (1.4 MHz) the UE can be scheduled with up to 6 physical resource blocks (PRBs) in any part of the cell BW if the cell BW is larger than 1.4 MHz. A minimum allocation of 1 PRB for both the uplink (UL) and downlink (DL) can be supported. For example if there are 5 MTC UEs in the same cell of 20 MHz BW. Then one can be configured in the center of the cell BW, with 2 UEs on the lower part of the cell BW and the remaining 2 UEs on the upper part of the cell BW.
Furthermore, the frequency of the MTC UE can also be re-tuned to support frequency multiplexing of users and to support frequency hopping across the cell BW. For example, a UE configured at a lower portion of the cell BW in a certain frame or subframe can be re-tuned to another part of the cell BW in another frame or subframe.
Narrow bandwidth MTC operation may also be referred to as narrow band operation or narrow band MTC operation. Currently in LTE the following 6 RF bandwidths are supported: 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz.
In flexible BW operation, UEs with a narrow bandwidth (i.e. an RF BW smaller than the cell BW) can be operated by the network node configuring them in any part of the cell BW. Furthermore, the UE and cell BW may be any possible BW with a resolution of one resource block (RB). As an example, in a cell of 20 MHz, two UEs with an RF BW of 6 MHz each may be configured to operate on a lower and an upper part of the cell BW, respectively. They may also be configured to operate with partial or full overlapping of their BWs within the cell. Flexible BW operation is similar to narrow BW MTC operation, except that in the case of flexible BW operation, there can be a larger number of possible RF BWs of the UE and of the cell.